This invention relates to gauges for inspecting parts which are generally flat and rectangularly shaped to insure that dimensions thereof are within prescribed limits and more particularly to a gauge for sorting dielectric substrate blanks into groups according to the magnitudes of the broad dimensions thereof.
Resistive and conductive patterns of hybrid circuits are formed by thick film techniques on thin rectangularly shaped dielectric substrates such as high purity alumina ceramic. A number of different printing operations must be performed sequentially on the substrates to produce these patterns on them. It is important that patterns produced during each operation be accurately located on the substrates. In order to achieve the desired accuracy, registry is normally made on the periphery of the substrates during each operation. Also, each operation is set to be performed on substrates having only specified lengths and widths that are within specified tolerances that are small. It is desirable therefore that the broad dimensions and warp of the substrate be carefully controlled. It is impractical, however, to set such tight manufacturing tolerances on substrates as would be required by these operations. It is therefore necessary to measure the length and width and warp of each substrate and to sort them into groups having different dimensional ranges. The various printing operations can then be performed first on one group and then on another group of substrates. The major dimensions and warp of substrates have previously been measured individually with handheld instruments in order to sort them into groups. Such a technique is time consuming. An object of this invention is the provision of improved semiautomated apparatus and method for more efficiently measuring and sorting substrates into groups according to ranges of dimensions thereof.